The 515 GN05 application measures the volume, mass and gross heat content of natural gas. The instrument uses single or stacked differential pressure inputs, as well as temperature and pressure sensor inputs.
The instrument calculates the flow according to AGA-3 differential pressure equations. The flow calculations incorporate the conditions at which the flowmeter was calibrated and accurately account for thermal expansion effect.
The AGA-8 Detail Characterization Method is used to obtain accurate values of density and compressibility factors for the flow calculations. For other gas properties, such as viscosity and isentropic exponent, the AGA-3 recommended values are used.
CALCULATIONS
The gas density and compressibility factor calculations are based on the AGA-8 equations. The calculations are valid for the region:
-130°C < t < 400°C P < 280MPa
-200°F < t < 760°F P < 40000psia
FORMULAS
volume flow =Mflow/ρflow
corrected flow = Mflow/ρ ref
Heat flow = Mflow•Hm
Where:
Mflow = mass flow
ρflow = density at flow conditions
ρ ref = density at reference conditions
Hm = mass gross heating value
